公开(公告)号：US20240424595A1

公开(公告)日：2024-12-26

申请号：US18698216

申请日：2022-09-29

Applicant: JFE STEEL CORPORATION

Inventor： Reiko ENDO ,  Katsutoshi TAKASHIMA ,  Hiroshi MATSUDA

IPC: B23K11/11 ,  F16B5/08

Abstract: A resistance spot welded joint having a resistance spot weld formed by resistance-spot-welding two or more steel sheets includes at least one high strength steel sheet. The high strength steel sheet has a specific chemical composition. The hardness Hv1 of a first region of a heat-affected zone and the hardness Hmv of martensite in a nugget as a whole satisfy the relation Hv1≤0.78×Hmw, and the hardness Hv2 of a second region of the heat-affected zone and the hardness Hv1 of the first region satisfy the relation Hv2≥1.10×Hv1. The hardness Hv3 of a third region of the heat-affected zone and the hardness Hv2 of the second region satisfy the relation Hv3≤0.90×Hv2.

公开(公告)号：US20240352959A1

公开(公告)日：2024-10-24

申请号：US18682746

申请日：2022-07-21

Applicant: JFE STEEL CORPORATION

Inventor： Reiko ENDO ,  Katsutoshi TAKASHIMA ,  Hiroshi MATSUDA

IPC: F16B5/08 ,  B23K11/11

CPC classification number: F16B5/08 ,  B23K11/115

Abstract: A resistance spot welded joint is formed by resistance-spot-welding two or more steel sheets including at least one high strength steel sheet. The high strength steel sheet has a chemical composition containing, in mass %, C: 0.05 to 0.6%, Si: 0.1 to 2.0%, Mn: 1.5 to 4.0%, and P: 0.10% or less, with the balance being Fe and incidental impurities. The hardness of a softest nugget region is 90% or less of the hardness of the heat-affected zone. The softest nugget region has a microstructure including tempered martensite. The average number density of carbide particles having a diameter of 100 nm or more in the softest nugget region is 10 or more per 5 μm2 in a cross section of the steel sheets.

公开(公告)号：US20240246167A1

公开(公告)日：2024-07-25

申请号：US18561363

申请日：2022-03-14

Applicant: JFE STEEL CORPORATION

Inventor： Katsutoshi TAKASHIMA ,  Reiko ENDO ,  Lingling YANG ,  Hiroshi MATSUDA

IPC: B23K11/16 ,  B23K11/00 ,  B23K11/11 ,  B23K101/00 ,  B23K103/04 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/20 ,  C22C38/22 ,  C22C38/46 ,  C22C38/54

CPC classification number: B23K11/166 ,  B23K11/0026 ,  B23K11/11 ,  B23K2101/006 ,  B23K2103/04 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/20 ,  C22C38/22 ,  C22C38/46 ,  C22C38/54

Abstract: An automotive member and a resistance spot welding method. The automotive member includes a resistance spot weld formed by resistance-spot-welding a plurality of steel sheets including at least one high strength steel sheet. The high strength steel sheet has a specific chemical composition. The microstructure in the vicinity of the edge of the nugget of the resistance spot weld is a composite microstructure containing ferrite at a volume fraction of 1 to 30%, martensite at a volume fraction of 1 to 50%, and tempered martensite at a volume fraction of 20% or more. The average number density of Nb-based precipitate grains having a grain diameter less than 0.09 μm and Ti-based precipitate grains having a grain diameter less than 0.09 μm is 10 or more grains per 100 μm2 in a sheet cross section.

公开(公告)号：US20230407447A1

公开(公告)日：2023-12-21

申请号：US18251422

申请日：2021-11-05

Applicant: JFE STEEL CORPORATION

Inventor： Shunsuke YAMAMOTO ,  Katsutoshi TAKASHIMA ,  Mai AOYAMA ,  Yusuke OKUMURA ,  Tomomi KANAZAWA ,  Katsuya HOSHINO ,  Hiroshi MATSUDA ,  Ei OKUMURA ,  Yoichi MAKIMIZU ,  Masaki KOBA

IPC: C23C2/02 ,  C22C33/04 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/38 ,  C22C38/32 ,  C22C38/28 ,  C21D9/46 ,  C21D8/02 ,  C21D6/00 ,  C22C38/00 ,  C21D1/74 ,  C25D5/36 ,  C25D5/48 ,  C25D3/56 ,  C23C2/28 ,  C23C2/40 ,  C23F17/00 ,  C23C28/00

CPC classification number: C23C2/02 ,  C22C33/04 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/38 ,  C22C38/32 ,  C22C38/28 ,  C21D9/46 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0278 ,  C21D6/002 ,  C21D6/005 ,  C21D6/008 ,  C22C38/002 ,  C22C38/001 ,  C21D1/74 ,  C25D5/36 ,  C25D5/48 ,  C25D3/562 ,  C23C2/28 ,  C23C2/40 ,  C23F17/00 ,  C23C28/34 ,  C23C28/321 ,  C21D2251/02 ,  B23K11/166

Abstract: Provided is a galvanized steel sheet with excellent resistance to cracking in resistance welding at a welded portion, even if crystal orientations of an Fe-based electroplating layer and a cold-rolled steel sheet are integrated at a high ratio at the interface between the Fe-based electroplating layer and the cold-rolled steel sheet. The galvanized steel sheet has a Si-containing cold-rolled steel sheet containing Si in an amount of 0.1 mass % to 3.0 mass %; an Fe-based electroplating layer formed on at least one surface of the Si-containing cold-rolled steel sheet with a coating weight per surface of more than 20.0 g/m2, and a galvanized layer formed on the Fe-based electroplating layer, where crystal orientations of the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet are integrated at a ratio of more than 50 % at the interface between the Fe-based electroplating layer and the Si-containing cold-rolled steel sheet.

公开(公告)号：US20230339037A1

公开(公告)日：2023-10-26

申请号：US17908799

申请日：2021-03-01

Applicant: JFE STEEL CORPORATION

Inventor： Reiko ENDO ,  Muneo MATSUSHITA ,  Yasuaki OKITA ,  Hiroshi MATSUDA

IPC: B23K11/11

CPC classification number: B23K11/115 ,  B23K2101/18

Abstract: Provided are a resistance spot welding method and a method for manufacturing a resistance spot welded joint. At least one of the steel sheets used is a high strength steel sheet. The method includes a main current application step in which current is applied with a current Iw and a tempering post-heat treatment step. The tempering post-heat treatment step includes a cooling process and a heating process and can include at least one of a transition process and a holding process. In the heating process, a current is applied at a current value It, shown in formula (2), for a current application time tt.


0.8×Iw≤It≤1.6×Iw   (2)

公开(公告)号：US20190203315A1

公开(公告)日：2019-07-04

申请号：US16325299

申请日：2017-08-29

Applicant: JFE STEEL CORPORATION

Inventor： Yoshie OBATA ,  Katsutoshi TAKASHIMA ,  Takashi KOBAYASHI ,  Hiroshi MATSUDA

IPC: C21D9/46 ,  C21D8/02 ,  C21D6/00 ,  C22C38/38 ,  C22C38/32 ,  C22C38/28 ,  C22C38/26 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C22C38/60 ,  C23F17/00 ,  B32B15/01

CPC classification number: C21D9/46 ,  B32B15/013 ,  C21D1/18 ,  C21D1/25 ,  C21D6/002 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0273 ,  C21D8/0278 ,  C21D8/0405 ,  C21D8/0426 ,  C21D8/0436 ,  C21D8/0463 ,  C21D8/0473 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008 ,  C22C18/04 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/18 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38 ,  C22C38/60 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40 ,  C23F17/00 ,  C25D3/22

Abstract: A high-strength cold rolled steel sheet having a specified chemical composition and a method for producing the same. The steel sheet having a microstructure including, in terms of volume fraction, 35% or less of ferrite, 1% or more and 10% or less of retained austenite, 2% or more and 12% or less of as-quenched martensite, and a total of 25% to 70% of bainite and tempered martensite. The microstructure has an average crystal grain diameter of the ferrite: 5.0 μm or less, an average crystal grain diameter of the retained austenite: 2.0 μm or less, an average crystal grain diameter of the as-quenched martensite: 3.0 μtm or less, an average crystal grain diameter of the bainite and the tempered martensite phase: 4.0 μm or less, and an average intergrain distance of the as-quenched martensite of 1.0 μm or more.

公开(公告)号：US20180043459A1

公开(公告)日：2018-02-15

申请号：US15555611

申请日：2016-02-16

Applicant: JFE STEEL CORPORATION

Inventor： Chikaumi SAWANISHI ,  Hiroshi MATSUDA ,  Rinsei IKEDA

IPC: B23K11/11 ,  B23K11/24 ,  B23K11/16

CPC classification number: B23K11/115 ,  B23K11/11 ,  B23K11/16 ,  B23K11/24

Abstract: A resistance spot welding method of squeezing a predetermined sheet combination by a pair of electrodes and passing a current while applying an electrode force to join the sheet combination includes: performing test welding; and performing actual welding after the test welding, wherein in each of the test welding and the actual welding, a current pattern is divided into two or more steps including a first current passage step and a second current passage step subsequent to the first current passage step, and, in the actual welding, a current that causes no expulsion is selected to perform welding by constant current control in the first current passage step, and adaptive control welding is performed from the subsequent second current passage step onward.

公开(公告)号：US20170175219A1

公开(公告)日：2017-06-22

申请号：US15327126

申请日：2015-08-05

Applicant: JFE STEEL CORPORATION

Inventor： Yoshiyasu KAWASAKI ,  Hiroshi MATSUDA ,  Yoshie OBATA ,  Shinjiro KANEKO ,  Takeshi YOKOTA ,  Kazuhiro SETO

IPC: C21D9/46 ,  C22C38/38 ,  C22C38/60 ,  C22C38/32 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C22C38/14 ,  C22C38/12 ,  C21D8/02 ,  C22C38/28

Abstract: Disclosed is a high-strength steel sheet having a predetermined chemical composition, satisfying the condition that Mn content divided by B content equals 2100 or less, and a steel microstructure that contains, by area, 25-80% of ferrite and bainitic ferrite in total, 3-20% of martensite, and that contains, by volume, 10% or more of retained austenite, in which the retained austenite has a mean grain size of 2 μm or less, a mean Mn content in the retained austenite in mass % is at least 1.2 times the Mn content in the steel sheet in mass %, and an aggregate of retained austenite formed by seven or more identically-oriented retained austenite grains accounts for 60% or more by area of the entire retained austenite.

公开(公告)号：US20250102009A1

公开(公告)日：2025-03-27

申请号：US18728240

申请日：2022-11-25

Applicant: JFE STEEL CORPORATION

Inventor： Katsutoshi TAKASHIMA ,  Shunsuke YAMAMOTO ,  Tomomi KANAZAWA ,  Katsuya HOSHINO ,  Hiroshi MATSUDA

IPC: F16B37/06 ,  B23K11/00 ,  B23K11/14 ,  B23K11/16 ,  B23K103/04 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C23C2/06 ,  C25D3/56 ,  C25D7/06

Abstract: A welded joint formed by performing projection welding on a high-strength coated steel sheet and a nut, includes a content of solid solution Mn in a first region in a surface layer of the steel sheet on an outermost periphery of a weld is 40% or less of a content of solid solution Mn in a second region in a central region in a thickness direction of the steel sheet on the outermost periphery of the weld, and a content of solid solution Mn in a third region in the surface layer of the steel sheet on an innermost periphery of the weld is 40% or less of a content of solid solution Mn in a fourth region in the central region in the thickness direction of the steel sheet on the innermost periphery of the weld.

公开(公告)号：US20240198443A1

公开(公告)日：2024-06-20

申请号：US18287320

申请日：2022-04-26

Applicant: JFE STEEL CORPORATION

Inventor： Kyohei KONISHI ,  Hiroshi MATSUDA ,  Koichi TANIGUCHI

IPC: B23K9/025 ,  F16B5/08

CPC classification number: B23K9/025 ,  F16B5/08

Abstract: An arc welded joint and an arc welding method. The arc welded joint has a weld formed by arc welding of an overlap of at least two steel sheets. The throat in the weld and the sheet that is uppermost among the steel sheets satisfy a specified relationship. In a region extending 2.0 mm from a bead toe of the weld in a weld metal direction and also extending 2.0 mm from the bead toe in a base material direction, a slag-covered area ratio is 50% or less.